error: Target grid must be a subset of source grid

[mt5555]

Trying to make a NE256 -> 1921x3840 mapping file with these commands:

% ncks -O -D 10 --rgr grd_ttl=FV-scalar-grid --rgr grid=1921x3840_SCRIP.nc
--rgr lat_nbr=1921 --rgr lon_nbr=3840 --rgr lat_typ=cap --rgr lon_typ=Grn_ctr
/tmp/bar.nc /tmp/foo.nc
% GenerateCSMesh --alt --res 256 --file TEMPEST_NE256.g
% GenerateOverlapMesh --a TEMPEST_NE256.g --b 1921x3840_SCRIP.nc --out overlap_mesh.g
% GenerateOfflineMap --in_mesh TEMPEST_NE256.g --out_mesh 1921x3840_SCRIP.nc
--ov_mesh overlap_mesh.g --in_type cgll --in_np 4 --out_type fv --out_double
--out_map map_ne256np4_to_1921x3840_highorder.nc

Which produces the error:
..EXCEPTION (src/LinearRemapSE0.cpp, Line 977) Target grid must be a subset of source grid

As these are both global grids, this must be an error?

[mt5555]

Output:

=========================================================
Parameters:
--in_mesh ["TEMPEST_NE256.g"]
--out_mesh ["1921x3840_SCRIP.nc"]
--ov_mesh ["overlap_mesh.g"]
--in_meta [""]
--out_meta [""]
--in_type ["cgll"] [fv|cgll|dgll]
--out_type ["fv"] [fv|cgll|dgll]
--in_np [4]
--out_np [4]
--bubble [false]
--mono [false]
--mono2 [false]
--mono3 [false]
--volumetric [false]
--noconserve [false]
--nocheck [false]
--var [""]
--out_map ["map_ne256np4_to_1921x3840_highorder.nc"]
--in_data [""]
--out_data [""]
--ncol_name ["ncol"]
--out_double [true]
--out_format ["Netcdf4"]
--preserve [""]
--preserveall [false]
--fillvalue [0.000000]
--in_concave [false]
--out_concave [false]

Initializing dimensions of map
..Input mesh
..Output mesh
Loading input mesh
..Mesh size: Nodes [393218] Elements [393216]
Loading output mesh
..SCRIP Format File detected
..22133756 duplicate nodes detected
..Mesh size: Nodes [7372804] Elements [7376640]
Loading overlap mesh
..Mesh size: Nodes [11521187] Elements [11523888]
..Calculating input mesh Face areas
....Input Mesh Geometric Area: 1.256637061435917e+01
..Calculating output mesh Face areas
....Output Mesh Geometric Area: 1.256637061435917e+01
..Overlap mesh forward correspondence found
Calculating overlap mesh Face areas
..WARNING: 16 small elements found
..Overlap Mesh Area: 1.256637846138206e+01
WARNING: Significant mismatch between overlap mesh area and input mesh area.
Automatically enabling --nocheck
Generating input mesh meta data
..Input Mesh Numerical Area: 1.256637061435937e+01
Calculating offline map
..Element 0/393216
...
..Element 294000/393216
..EXCEPTION (src/LinearRemapSE0.cpp, Line 977) Target grid must be a subset of source grid

[mt5555]

same error with a smaller lat/lon grid: 801x1600

But 401x800 works and does not produce that error.

[mt5555]

same error with when mapping NE1024 → 3073x6144, with the 3073x6144 grid generated with TR's GenerateRLLMesh, but the code doesn't crash with an NCO generated 3073x6144 grid.